TO BE COMPLETED BASED UPON STATISTICS --
Spring begins next Monday (1 March 1999) - at least in terms of the meteorological seasons. For many areas of the country, spring-like conditions have prevailed for the last month. However, for the residents of the Black Hills of South Dakota, the sight of deep snow banks makes spring seem distant. So before we can close the books on the three month winter season (December, January and February) we should take a look to see its severity.
One could inspect the tables of monthly average temperature and precipitation that are furnished by the National Weather Service at the beginning of each month for selected U.S. cities. The parade of storms across the southern tier of states produced excessive precipitation totals in California, where 10 to 15 inches above what typically falls in winter fell this past winter. Many locations across the northern tier of states reported one of their warmest winters on record, including Marquette, MI and Portland, ME.
To put this in perspective, one familiar gauge of the winter's severity is the amount of heating fuel that we need to use to keep our homes warm over the winter. In other words: How has the winter of 1997-1998 affected our pocket books when it comes to space heating?
The heating degree day unit has been a useful indicator that gauges the amount of energy required for space heating. Using recently compiled data through February 1998, the Climate Analysis Center of the National Weather Service has computed the number of heating degree day units accumulated during February and over the heating season that started last 1 July for selected cities around the country. These monthly and seasonal values are compared with the corresponding values for last year to date and for the "normals" representing the 30 year averages for the current 1961-1990 climatological reference interval. The climatologists at the Climate Analysis Center have also prepared a corresponding list of population weighted heating degree day units for each state. These latter statistics are used to show more accurately the temperature-related energy consumption on the state, regional, and national levels.
Their results indicate that over the entire heating season to date, most of the county has faired well in terms of fuel consumption based upon the accumulated number of heating degree day units since last July. Nationally 8 percent fewer number of heating degree day units were accumulated this season as compared to the "normal", and 5 percent fewer as compared with last season. The only regions that required more heating units included portions of the Gulf Coast, centered over Mississippi and Alabama and over the southern Rockies, especially in New Mexico and southern Colorado. These two regions experienced a small positive departure from the long term "normal". The relatively mild weather across the northcentral states lead to a 10 percent reduction in the heating units as compared with normal in both the eastern and western Northcentral States. Since the previous winter was cold across the Dakotas, this season showed a 14 percent reduction as compared with last season in the western Northcentral States.
Corresponding sets of cooling degree day units for selected cities and for population weighted regions were also compiled. Since the cooling season only started on 1 January and most locales have not experienced daily average temperatures above 65 degrees, analysis of these statistics is somewhat premature. However, because of the warm weather, South Florida and the lower Rio Grande Valley of South Texas have had more cooling degree day units accumulated since the beginning of the year than normal. Other warm-weather locales have been chilly and therefore accumulated fewer cooling units than typical over the first two months of the cooling season.
Ultimately, the "bottom line" has been that for most residents across the country, to date, the abnormally mild winter weather would demand less energy as compared to the long term average and therefore not strain the pocketbook - assuming that monetary inflation or other non-weather related price increases are not taken into account.
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Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 1999, The American Meteorological Society.